California Code, Business and Professions Code - BPC § 3600-5

Notwithstanding any other provision of law, on and after the effective date of this section, a graduate of an osteopathic medical school shall apply for a physician's and surgeon's certificate from the Osteopathic Medical Board of California, which has the sole power to issue a physician's and surgeon's certificate to an osteopathic-trained physician and surgeon.

It shall be unprofessional conduct for a physician and surgeon licensed by the Osteopathic Medical Board of California to apply for a physician's and surgeon's certificate from a board other than the Osteopathic Medical Board of California.

This section shall not prohibit the renewal of a physician's and surgeon's certificate which was issued by a board other than the Osteopathic Medical Board of California prior to the effective date of this section.